1. Field of the Invention
This invention relates generally to a system and method for the recovery and reintroduction of atmospheric vented gases and more particularly to the recovery and reintroduction of gases and fluids generally discharged into the environment from hydrocarbon separation systems used in production, process and transmission systems.
2. General Background
Eductors or jet pumps have been in use for many years in different applications as a means of pumping, vacuuming, and mixing in a great many applications. Eductors are simple to build and operate with essentially no mechanical parts to break down. The Eductor operates on the principle of a venturi, through which an energized fluid is directed causing a differential pressure across an orifice situated in a mixing chamber. The mixing chamber has a port to allow fluids or gases at a static or lower pressure than the energizing fluid pressure to be drawn into the chamber due to the created differential between the energized or pressurized line and the static or lower pressure inlet lines . The fluids or gases being drawn into the chamber mix with the energized fluid or gases resulting in a mixture of both fluids and or gases as result of the pressure differential between the energized fluid or gases and the fluid or gas being drawn into the mixing chamber from the static or lower pressure inlet line. The pressure and volume of the mixed fluids may be adjusted by controlling the energized and static inlet fluid volume and pressure with a restricting device installed in the inlet lines to the Eductor. The mixed fluid departs the chamber at a reduced pressure less than the inlet energized fluid, but greater than the static or lower pressure fluid or gas being drawn into the mixing chamber. Although various systems using such Eductors have been developed for vapor recovery in handling volatile liquids which emit toxic gas, such as those disclosed by U.S. Pat. Nos. 3,817,265, 5,135,360, 5,139,390, 5,195,587, 5,207,249, 5,325,896, 5,651,389 and 5,957,665. Even closed loop systems such as that disclosed by U.S. Pat. No. 5,516,119 have proven effective in controlling gas emission. However, Eductors are primarily used as mixing and stripping systems such as is disclosed by U.S. Pat. Nos. 3,648,434 and 5,209,762. Other systems utilize various methods for capturing vapors emitted from gas dehydrators, oil storage tank, and catalytic cracking processes while still others utilize a venturi type apparatus for capturing vapors emitted from gasoline being transferred into tanks.
A system utilizing the eductor, or jet pump, although not new to the art, has not been utilized in the manner taught herein for use in gas/oil production, processing or transmission systems for collectively recovering hydrocarbon fluids and gases, including greenhouse gases such as methane, ethane, and hydrocarbon compounds, VOC""s, Volatile Organic Compounds that react and produce ozone in the lower atmosphere, HAP, Hazardous Air Pollutants including benzene, toluene, ethybenzene, xylene, n-hexane, 2-2-4 trimethyl pentane, and CO and NOX, gas produced from combustion and/or released from natural gas, as well as many other air pollutants currently being vented into the atmosphere from the various stages of a hydrocarbon separation processing systems for reinjection and recirculation within the processing system without the use of any external energy or powered mechanical pumps etc.
Some current systems use compressors to produce condensation for dilution, while others use flares or mix the exhaust gases and fluids with other fuel gases to produce fuel to be burned in engines or heater burners utilized with the hydrocarbon processing system itself . These existing processes create combustion emissions (CO and NOX) themselves which must also be exhausted. In some cases these systems use outside energy sources such as electricity or natural gas to operate and are therefore more costly than the process disclosed herein utilizing the EVRU.
Therefore, there is a need for an efficient, economical system capable of capturing hydrocarbon emissions from the various vented exhaust ports within separation systems used for production, processing and transmission of oil and gas and reintroducing the vented contaminates in a closed loop system back into the system without interrupting or using any additional energy.
The disclosed EVRU or Eductor Vapor Recovery Unit disclosed herein serves to collect, contain and recycle emissions generally exhausted or otherwise emitted into the atmosphere from hydrocarbon separation systems used in processing hydrocarbons chemicals etc., including the production and transmission process of such hydrocarbons and chemicals through sales lines etc. in a manner resulting in a closed loop system. The vapor recover process herein taught is directed primarily to the recovery of vapors emitted from hydrocarbon separation and reactor processes and the reintroduction of such vapors with no external energy source and not to eductor type units used for vapor recovery used in external fuel tank vapor recovery for fuel distribution or fuel blending systems and the like. The EVRU is considered far superior to other methods and processes presently in service within the hydrocarbon separation processing systems as discussed above.
The EVRU essentially includes an eductor or jet pump operating on the venturi principle as its core element. The system further includes flow safety valves, flow measuring elements, a flow control mechanism, pressure sensing devices, and temperature sensing and indicating devices. Pressure and temperature isolating valves are also installed in the energized fluid line entering the eductor for replacing or repairing of these devices.
In operation, the eductor inlet or energized fluid or gas inlet receives the energized fluid which passes through the venturi orifice, thereby creating the desired differential pressure determined by the controlled energized fluid pressure and volume regulated by the inlet flow control mechanism. The energized EVRU fluid or gas volume is proportional to the volume of the fluids or gases being drawn from the lower pressure emission vents of the static hydrocarbon process system to which the EVRU is attached, as a result of the pressure differential created by the, EVRU jet pump venturi. The static or low pressure emissions (greenhouse gases, VOC""s, HAP""s, CO and any other air pollutants) line entering the eductor further includes a directional flow valve to prevent back pressure from over-pressurizing the vessel. Also included are a flow measuring element to measure the volume of fluids being recovered from the vessel, a pressure sensing device to determine the emission (greenhouse gases, VOC""s HAP""s, CO2 and any other air pollutants) fluid pressure entering the eductor, as well a temperature sensing and. indicating device to assist with the control of the emissions fluid entering the eductor. Pressure and temperature isolating valves are also installed in the emission fluid line entering the eductor for replacing or repairing of these devices. The eductor emissions fluid inlet receives vapor emissions and/or liquids and mixes these fluids with the energized fluid in the mixing chamber. The mixed fluids converge and flow through the eductor outlet and through the outlet line. The outlet line consists of a pressure sensing device to determine the mixed fluid pressure departing the eductor and a temperature sensing and indicating device to assist with the control of the mixed fluid departing the eductor. Pressure and temperature isolating valves are installed in the mixed fluid line departing the eductor for replacing or repairing of these devices. The mixed fluid outlet also contains a flow safety device to prevent back flow and over-pressurizing of all components upstream of the flow safety device. The final destination of the mixed fluids (energized fluid and emissions (greenhouse gases, VOC""s, HAP""s, CO and any other air pollutants)) is a compatible hydrocarbon processing vessel having an operating pressure less than the energized fluid, greater than the emissions fluid, and slightly less than or equal to the mixed fluid pressure which closes the system by recycling the emissions back into the processing system and ultimately out through the gas or oil sales pipe lines and/or the water disposal lines.